1. Field of the Invention
This invention relates to a wiring system for tank trailers to simplify installation and maintenance
2. Prior Art Statement
Existing wiring looms for fuel overfill sensing systems on tractor trailer tankers consists of multiple pieces of multi-stranded wiring cable daisy-chained from sensor to sensor in the drain channel on top of the tank truck. The overfill sensing system usually operates at about 250 milliamps at 12.8 volts DC. Since the cabling is a special tin coated wire and cannot be soldered, installation requires a skilled electrician as each wire must be fitted with a crimp connector and hand assembled to each sensor, the cabling daisy-chained to the next sensor and subsequent sensors, the cabling routed to and connected to the onboard monitor with separate links made from the onboard monitor to the API interface sockets. Since a five compartment tanker truck uses a six wire cable, each sensor has twelve wire ends and hence twelve connections, the time required to install a system on a five compartment tank trailer often approaches 10 man-hours for a skilled electrician. Tank trucks with fifteen compartments more than quintuples the time required as each sensor now needs thirty connections, fifteen in and fifteen out to complete the daisy-chain. A major maintenance problem then exists at the hand assembled joints as they are subject to intrusion by environmental factors, including, but not limited to, water, sand, grit, dust, fuel, vibration, scuffing and the like because the sensor body connections are not fluid tight resulting in corrosion of the internal body of the sensor, the monitor or the API socket, any of which causes loss of electrical connection. Some tank trucks require repair within 3 months of initial assembly since all connections are made through mechanical compression fittings disposed in the sidewall of the sensor bodies and the monitor box and these mechanical fittings are not fully fluid tight. Additionally, the cabling used for wiring is not fully water and fuel resistant and hence deterioration of the insulation on the cabling causes additional failures. Failure most often is discovered at fuel delivery when the API sockets connecting the tanker to the fueling facility detect an onboard system failure in the overfill warning system and the driver is denied authorization for fueling thus requiring the tank trailer driver to have the system overhauled before delivery can be started, resulting in downtime and lost income.